#include<bits/stdc++.h>
using namespace std;

int main() {
	freopen("number.in", "r", stdin);
	freopen("number.out", "w", stdout);

	string s;
	cin >> s;

	int a[10] = {0};
	for (int i = 0; i < s.length() ; i ++)
		if (s[i] >= '0' and s[i] <= '9')
			a[s[i] - '0']++;

	for (int i = 9 ; i >= 0 ; i --)
		while (a[i]) {
			cout << i;
			a[i]--;
		}


	return 0;
}
